1. Field of the Invention
The present invention relates generally to heads for erasing signals imprinted upon a magnetic medium, and more particularly to an AC erase head having an irregular or jagged-edged gap defined therein. Further, the present invention relates to a preferred method of producing such magnetic head by thermally etching the ferrite material of half core elements defining the edges of the gap.
2. Description of the Prior Art
Magnetic heads, in general, are well known. There exists a great deal of expertise attendant thereto. Broadly, magnetic heads classically comprise a pair of half core elements defining a narrow gap therebetween. The half core elements are integrally joined, in most instances, or alternatively, connected by a yoke portion which confines the magnetic field between the core elements. Electrical windings are coupled to the core elements to induce a signal in the core.
Heretofore, the bulk of the art relating to magnetic heads have, in general, been concerned with recording heads and have suggested rather substantial efforts and involved processes to insure a smooth, regular edge at the surfaces defining the gap. Since it is necessary that the gap be filled with a non-magnetic material, preferably a solid such as a vitreous material, and since such vitreous materials often erode the more desirable of the materials for the half core elements such as ferrite, particular attention has been paid to grain direction, polishing, etc. in finishing the heads and defining the gap in order that smooth, regular edges may be produced.
U.S. Pat. No. 2,945,919 issued July 19, 1960 is typical of such prior art magnetic heads, and particularly is typical of the means employed to provide smooth gap surfaces. According to this teaching, the relatively rough ferrite surfaces which initially form the gap are covered with a layer of another ferromagnetic material which in turn is polished to provide the, according to the patent, desirable regular and smooth gap defining surfaces.
U.S. Pat. No. 3,810,245 issued May 7, 1974 discusses the ramifications of orienting ferrite single crystal materials in order to expose favorable crystal planes through which the crystal may be cut or ground to provide smoother surfaces.
In summary, magnetic heads have heretofore been troubled with occasional minor roughness at the gap surfaces, but procedures have been developed to obviate this shortcoming and to provide a smooth, regular gapped surface.